煤矿井下近水平钻孔大直径套管长距离下放技术
Long distance running technology of large-diameter casingwith near horizontal drilling in underground coal mine
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摘要: 孔口套管封孔是后续钻孔施工与安全保障的基础，大直径套管通过能力、套管孔段轨迹偏斜控制和钻孔排渣效果是影响煤矿井下大直径套管近水平长距离下放成功的关键。为了提高套管近水平长距离下的成功率，建立了大直径套管刚性模型和弹性模型 ，获得了煤矿井下常用178 mm、146 mm和127 mm套管在弯曲钻孔的通过能力数据；分析了近水平大直径套管孔段排渣困难与易发生偏斜的原因，提出采用大直径螺旋钻杆与内凹式PDC钻头进行保直钻进和高效排渣的技术方案，开发了相关钻具，制定了钻具组合，并分析了保直钻进和高效排渣机理。在赵固一矿进行了现场试验，完成3个钻孔施工，与常规工艺相比，套管孔段施工时间由110班次缩短至21班次，轨迹偏斜仅为0.042°/m，套孔下放成功率达到100%，有效解决了大直径套管近水平长距离下放难题。Abstract: The sealing of drill hole casing is the basis of drilling construction and safety guarantee. The key factors affecting the installation success rate of large diameter casing with near horizontal and long distance in coal mine are the passing capacity of large diameter casing, the deviation control of hole trajectory and the effect of slag discharge.In order to improve the pasing success rate of casing with near horizontal and long distance.The rigid and elastic models of large diameter casing were established, and the passing capacity of ø178mm,ø146 mm and ø127mm casing in the underground coal mine was obtained. The causes of easy deviation and difficult slag discharge in near horizontal and large diameter casing borehole section were analyzed, and the technical scheme of using large diameter auger drill rod and concave PDC drill bit for straightening drilling and efficient slagging was introduced. The related drilling tools were developed, the drilling tool assembly was also made, and the mechanism of straight drilling and high-efficiency slag discharge was analyzed. Field test was carried out in Zhaogu No.1 coal mine, and three boreholes were completed for it. Compared with the conventional process, the construction time of casing borehole section was reduced from 110 to 21 shifts, the trajectory deflection was only 0.042 °/m. The success rate reaches 100%, which effectively solves the problem of large-diameter casing with near horizontal and long distance and provides reference for similar casing borehole section construction.
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